Assuming that DC.503 is the same as 503 BC, then it commemorates the date of the first run of the Desert Speeder on the Cairo Metro Giza underworld line.
Egypt had been conquered by the Persian Empire in 525 BC, so it was the Achemenid Pharaoh Darius the First who was on the throne at the time. He was known to be very keen on updating Egypt's archaic transport system, which up until then had run almost entirely with slave-powered locomotives, never very reliable at the best of times.
The Desert Speeder was of course powered by the star-gate drive unit that had been left in the Great Pyramid by the last lot of visiting aliens.
Egypt had been conquered by the Persian Empire in 525 BC, so it was the Achemenid Pharaoh Darius the First who was on the throne at the time. He was known to be very keen on updating Egypt's archaic transport system, which up until then had run almost entirely with slave-powered locomotives, never very reliable at the best of times.
The Desert Speeder was of course powered by the star-gate drive unit that had been left in the Great Pyramid by the last lot of visiting aliens.
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